Modular glenoid prosthesis

ABSTRACT

A method for assembling a glenoid assembly. The method includes using a base having a first side and an opposing second side. The first side includes a plurality of connection features arranged in an array. The method further includes using a plurality of glenoid attachment members, wherein each of the plurality of glenoid attachment members has a locking mechanism. One of the plurality of glenoid attachment members is selected and is connected to the base by connecting the locking mechanism of the selected one of the plurality of glenoid attachment members to one of the plurality of connection features of the base.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a divisional application of U.S. patent application Ser. No.12/953,522 entitled “MODULAR GLENOID PROSTHESIS,” which is incorporatedherein by reference in its entirety. Cross reference is made to thefollowing application: DEP6346USNP, U.S. patent application Ser. No.12/953,519 entitled “MODULAR GLENOID PROSTHESIS” filed Nov. 24, 2010,which is incorporated herein by reference in its entirety.

TECHNICAL FIELD

The present invention relates to a prosthetic glenoid component andparticularly to a modular glenoid assembly for attachment to a glenoidsurface of a scapula to replace a natural socket of a shoulder and toprovide a bearing surface for a head portion of an arm bone or humerus.

BACKGROUND

During the lifetime of a patient, it may be necessary to perform a totalshoulder replacement procedure on the patient as a result of, forexample, disease or trauma. In a total shoulder replacement procedure, ahumeral component having a head portion is utilized to replace thenatural head portion of the arm bone or humerus. The humeral componenttypically has an elongated intramedullary stem which is utilized tosecure the humeral component to the patient's humerus. In such a totalshoulder replacement procedure, the natural glenoid surface of thescapula is resurfaced or otherwise replaced with a glenoid componentwhich provides a bearing surface for the head portion of the humeralcomponent.

Glenoid components have heretofore been designed which include a numberof plastic inserts coupled to metal backings The metal backings areprovided to secure the plastic inserts to the glenoid surface of thescapula. However, use of such two-piece glenoid components has a numberof drawbacks associated therewith. For example, it is possible over theuseful life of the glenoid component for the plastic inserts to separatefrom the metal backing thereby necessitating replacement of the glenoidcomponent. In addition, over time wear of the plastic insert inherentlyoccurs at the interface between plastic insert and the metal backing. Itis possible for the plastic insert to wear to a degree whichnecessitates replacement of the glenoid component. It should beappreciated that in either case, such replacement of the glenoidcomponent requires the patient to again be subjected to a surgicalprocedure and the subsequent recovery period associated therewith.

In response to the shortcomings associated with two-piece glenoidcomponent designs, a number of one-piece glenoid components haveheretofore been designed. In regard to such one-piece designs, a bodyportion, having a bearing surface defined therein for receiving the headof the humeral component, has a number of attachment pegs integrallyformed therewith. The attachment pegs are advanced and thereaftersecured into a corresponding number of holes which are drilled in theglenoid surface of the scapula by use of bone cement. An example of sucha one-piece glenoid component that is designed to be secured to thescapula by use of bone cement is disclosed in U.S. Pat. No. 5,032,132issued to Matsen, III et al.

As with the two-piece designs, certain one-piece glenoid componentswhich have heretofore been designed have a number of drawbacksassociated therewith. For example, some studies have speculated that itmay be desirable to secure artificial components to natural bonestructures without the use of bone cement. Glenoid components which havebeen designed to be secured to the scapula by the use of bone cementgenerally cannot be secured to the natural glenoid without use of thesame.

Many glenoid component designs have been manufactured to addressdifferent types of scapular deficiencies. For example, some glenoidcomponents have anchor pegs with flexible fins that are designed to actas barbs when inserted into the scapula. Other designs may utilizeglenoid components with a buttress extending from the glenoid to filllarger defects in the natural glenoid. These may also include anchorand/or stabilizing pegs. In other embodiments a vault-filling glenoidmay be used to fill a natural glenoid that has severe defects.

However, one problem with even existing modular designs, is that they donot provide the surgeon with the option of using different designs oncesurgery has started. Also, if a kit was to include all the differentsizes and variations, the kit would be quite large and cumbersome tobring into surgery.

Another problem is that glenoid bone quality and surface deteriorationvaries significantly from patient-to-patient. Therefore, in currentdesigns, having standard peg or buttress or vault locations may not workwith specific patients' anatomy.

Another problem faced by surgeons during the procedure is that if theglenoid is partially eroded, ligament tensioning may be less than ideal.In some prior art designs, a stepped glenoid is provided to allow thesurgeon to fill the eroded glenoid. However, these glenoids come inpredetermined sizes and the size of the step (height and width) may notappropriately fill the glenoid erosion.

SUMMARY

According to one embodiment of the present invention, a modular glenoidassembly is provided. The modular glenoid includes a base having a firstside and an opposing second side. The first side includes a plurality ofconnection features arranged in an array. The modular glenoid alsoincludes at least one glenoid attachment member, the glenoid attachmentmember having a locking mechanism sized and shaped to lock the glenoidattachment member in at least one of the plurality of connectionfeatures on the base.

According to another embodiment of the present invention, a kit for usein a shoulder arthroplasty is provided. The kit includes a modularglenoid assembly. The modular glenoid assembly includes a base having afirst side and an opposing side. The first side includes a plurality ofconnection features arranged in an array. The modular glenoid assemblyfurther including a glenoid attachment member selected from a pluralityof glenoid attachment members. Each of the plurality of glenoidattachment members have a locking mechanism sized and shaped to connectthe base with the glenoid attachment member. At least one of theplurality of glenoid attachment members has a shape different than atleast one other of the plurality of glenoid attachment members andwherein the locking mechanism of each of the plurality of glenoidattachment members is the same.

According to yet another embodiment of the present invention, a methodfor assembling a glenoid assembly is provided. The method includes usinga base having a first side and an opposing second side. The first sideincludes a plurality of connection features arranged in an array. Themethod further includes using a plurality of glenoid attachment members,each of the plurality of glenoid attachment members having a lockingmechanism. One of the plurality of glenoid attachment members isselected. The base is connected to the selected one of the plurality ofglenoid attachment members by connecting the locking mechanism of theselected one of the plurality of glenoid attachment members to one ofthe plurality of connection features of the base.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a glenoid assembly according to oneembodiment of the present invention.

FIG. 2 is a side view of a base of the glenoid assembly of FIG. 1.

FIG. 3 is a perspective view of an offset of the glenoid assembly ofFIG. 1.

FIG. 4 a is a side view of a cemented peg of the glenoid assembly ofFIG. 1.

FIG. 4 b is a side view of an anchor peg of the glenoid assembly of FIG.1.

FIG. 5 is a perspective view of the modular glenoid assembly of FIG. 1positioned between a glenoid surface of a scapula and a humeralcomponent.

FIG. 6 is a perspective view of a glenoid assembly according to anotherembodiment of the present invention.

FIG. 7 is a perspective view of a wedge-shaped filler of the glenoidassembly of FIG. 6.

FIG. 8 is a perspective view of a glenoid assembly according to anotherembodiment of the present invention.

FIG. 9 is a perspective view of another glenoid assembly according toanother embodiment of the present invention.

FIG. 10 is a perspective view of an augment according to the glenoidassembly of FIG. 8 or 9.

FIG. 11 is an illustration showing a kit for making a modular glenoidassembly according to one embodiment of the present invention.

FIG. 12 is a flow chart illustrating a method for assembling the modularglenoid assembly according to one embodiment of the present invention.

Additional features of the present invention will become apparent tothose skilled in the art upon consideration of the following detaileddescription of preferred embodiments exemplifying the best mode ofcarrying out the invention as presently perceived.

DETAILED DESCRIPTION OF THE DRAWINGS

A modular glenoid assembly 10 is provided in accordance with the presentinvention. FIG. 1 shows glenoid assembly 10 including a base 12, anoffset 14, and a glenoid attachment member 16. As shown in FIGS. 1 and2, the base 12 includes a first side 18 and a second side 20. The firstside includes a plurality of connection features 22 arranged in anarray. The second side 20 of the base 12 includes a locking feature 23.In this embodiment, the locking feature 23 is a pair of receptacles 24.

Turning now to FIG. 3, the offset 14 is illustrated. The offset includesan articulation side 25 an opposing coupling side 26. The articulationside 24 is sized and shaped to articulate with a humeral component(discussed further below with respect to FIG. 5). The opposing couplingside 26 includes a locking feature 28. In this embodiment, the lockingfeature 28 is a pair of protrusions 30 that lock into the receptacles 22of the base 12. In other embodiments, other known locking features maybe used, such as dovetails, and snap locks.

Referring now to FIG. 4, a plurality of glenoid attachment members 16are shown. In this embodiment, the glenoid attachment member 16 includesa finned anchor peg 32 and a plurality of cemented pegs 34. Each of theglenoid attachment members 16 include a locking mechanism 36 sized andshaped to lock the glenoid attachment member 16 into at least one of theplurality of connection features 22 on the base 12. In the embodimentillustrated in FIGS. 1 and 4, each of the finned anchor peg 32 andcemented pegs 34 have a locking mechanism 36.

In this embodiment, the locking mechanism 36 is a ball-shaped member 38and the connection features 22 are each generally spherical shapedreceptacles 40 that are sized and shaped to lock the ball shaped member38 into place. As described above, the generally spherical shapedreceptacles are arranged in an array. In this embodiment, each of theconnection features is the same size, allowing for the user to place theglenoid attachment members 16 anywhere along the array. Giving the userthis flexibility allows the user to select the best location for theattachment members 16 based upon bone stock or other considerations.Also, because the locking mechanism 36 and the connection features 22are generally spherical (balls and receptacles respectively) the usermay insert the finned anchor peg 32 and/or cemented pegs 34 at a varietyof different angles.

In other embodiments, the locking mechanism 36 may be of a differentsize, so long as it is able to lock into the connection feature 22.Furthermore, in other embodiments, the finned anchor pegs 32 andcemented pegs 34 may be of different sizes and shapes.

Turning now to FIG. 5, the glenoid assembly 10 is shown located betweena glenoid surface 41 of a scapula 42 and a head portion 44 of a humeralcomponent 46. Glenoid assembly 10 is designed to be attached to glenoidsurface 41 of scapula 42 to replace the natural glenoid surface. Asshown, the finned anchor peg 32 and cemented pegs 34 correspond to holes43 drilled into the glenoid surface 41. The finned anchor peg 32 andcemented pegs 34 will be placed in the holes 44, locking the glenoidassembly 10 to the glenoid surface 40.

The articulation side 24 of the offset 14 is smooth and will articulatewith the head portion 44 of the humeral component 46. In someembodiments, the head portion 44 may also be an implant. In otherembodiments, the head portion 44 may be the natural humeral head.Although this embodiment shows the offset 14, in some embodiments, thebase 12 may not need to be coupled to an offset and the second side 18of the base 12 may be used to articulate directly with the head portion44 of the humeral component. In those embodiments, the base 12 may notinclude the locking feature 23 described above.

Turning now to FIGS. 6 and 7, the base 12 is illustrated coupled to theoffset 14 and the glenoid attachment member 16. In this embodiment, theglenoid attachment member 16 is a wedge-shaped filler 48. Thewedge-shaped filler is designed to fill a defect (not shown) in theglenoid 41 (FIG. 5) and to couple the base 12 and offset to the glenoid41. The wedge-shaped fill 48 includes a locking mechanism 50. In theembodiment illustrated in FIGS. 6 and 7, the locking mechanism 50 is aball-shaped member 52. The ball-shaped member 52 is the same size as theball-shaped member 38 of the anchor peg 32 and cemented pegs 34. Byutilizing the same dimensioned locking mechanisms 36, 50, both thewedge-shaped filler 48 and the pegs 32, 34 can be used with the samebase 12.

Another component of the present invention is illustrated in FIGS. 8-10.In this embodiment, the base 12 is coupled to an offset and a pluralityof glenoid attachment members 16. In this embodiment, the glenoidattachment members 16 are augments 54. The augments 54 are designed tofill defects in the glenoid 41. The augments 54 may be of differentheights, allowing the surgeon to fill different sizes of defects withinthe glenoid. Each of the augments 54 includes a locking mechanism 56designed to fit within the connection feature 22 of the base 12. In theillustrated embodiment, the locking mechanism 56 of each of the augments54 is a ball-shaped member 58 that fits into the generally sphericalrecesses 40 of the base 12. As stated above, by having the ball-shapedmember 58 be of the same size as the ball-shaped members 38, 52 of thepegs 32, 34, and wedge-shaped filler 48 allows the user to use a singlebase 12 with multiple components, depending upon the needs of thepatient.

As shown in FIG. 8, two differently sized augments 54 are coupled to thebase. Alternatively, the user could select more augments 54 as shown inFIG. 9. FIGS. 8 and 9 are merely examples, any number of augments 54 maybe used depending upon the defect to be corrected.

Turning now to FIG. 11, a kit 60 is illustrated. The kit 60 includes abase 12, a plurality of offsets 14 a, 14 b, 14 c, and a plurality ofglenoid attachment members 16 a, 16 b, 16 c, 16 d. As shown, each of theplurality of offsets 14 a, 14 b, 14 c has a different height h_(a),h_(b), h_(c). By offering offsets 14 a, 14 b, 14 c of differing heights,the user can pick an offset to fit an individual patient's needs. Theoffsets 14 a, 14 b, 14 c, allow the user (in this case a surgeon orother operating room personnel) to select an offset that will bestrestore ligament and/or tendon tension to the joint. The differing sizesof offsets allows the user to lateralize the humerus depending upon thepatient. The user may choose to lateralize the humerus more in order totighten the rotator cuff. Differing numbers of offsets 14 may beincluded.

The plurality of glenoid attachment members 16 include a plurality ofcemented pegs 34, a finned anchor peg 32, a wedge-shaped filler 48, anda plurality of augments 54. In other embodiments, other numbers of eachof the glenoid attachment members 16 may be included. Also, in someembodiments, some of the attachment members 16 may not be included. Inother embodiments, there may be other glenoid attachment members 16 suchas pins, screws, nails, un-finned anchor pegs.

The plurality of different types of glenoid attachment members 16 allowsthe user (such as a surgeon) to select the type of glenoid attachmentmember 16 that bests suits the individual patient. For example, if thepatient's glenoid is relatively healthy, the surgeon may use only thefinned anchor peg 32 and one or more cemented pegs 34. If there isslightly worse wear, the surgeon may use one or more of the augments 54.In some embodiments, the augments 54 may be used in conjunction withanchor pegs 32 and/or cemented pegs 34. Any number and combination ofaugments 54 may be used to best fit the patient's needs. In cases wherethe patient has experience sever wear and deterioration of the glenoid,the wedge-shaped filler 48 may be used.

One advantage of the kit 60 as illustrated other than the ability to mixand match is that each of the glenoid attachment members 16 has the samelocking mechanism and that the connection features 22 are all sized andshaped the same. This allows the user to place the attachment members 16into any of the connection features 22, depending on the patient'sanatomy.

In the illustrated embodiment, the base 12, offsets 14, and glenoidattachment members 16 are all made of ultra-high molecular weightpolyethylene. In other embodiments, the base 12, offsets 14, and glenoidattachment members may be manufactured using biocompatible metals orother biocompatible plastics. Alternatively, it is also contemplatedthat the base 12, offsets 14, and glenoid attachment members 16 may notall be manufactured using the same materials.

Turning now to FIG. 12, a flow chart illustrating a method according toone embodiment is illustrated. At step s102, the method includes usingthe base 12 and a plurality of attachment members 16. The base 12 has afirst side 18 and an opposing second side 20. The second side 20includes a plurality of connection features 22. Each of the plurality ofattachment members 16 includes a locking mechanism 36. At step s104, oneof the plurality of glenoid attachment members 16 is selected. The base12 is then connected to the selected one of the plurality of glenoidattachment members 16 by connecting the locking mechanism 36 of theselected one of the plurality of glenoid attachment members 16 to one ofthe plurality of connection features 22 of the base 12 (step s106). Asdescribed above, the plurality of glenoid attachment members 16 mayinclude finned anchor pegs 32, cemented pegs 34, wedge-shaped fillers48, and augments 54 and the locking mechanism 36 of each of theplurality of glenoid attachment members 16 is the same, so that any ofthe glenoid attachment features 16 may be locked into the base 12.

In some embodiments, the user may decide to insert the selectedattachment member 16 first into the drilled glenoid 41. Next, the userwill then lock the base 12 onto the selected attachment member 16. Inother embodiments, the user may pre-assemble the base 12 and theselected attachment member 16 prior to inserting the implant 10 into theglenoid 41.

In some embodiments, the method may further include using a plurality ofoffsets 14 and selecting one of the plurality of offsets 14. Theselected offset 14 is then connected to the base 12 as described abovein reference to FIGS. 1-5.

Although the invention has been described in detail with reference to apreferred embodiment, variations and modifications exist within thescope and spirit of the invention as described and defined in thefollowing claims.

1. A method for assembling a glenoid assembly, the method comprising:using a base having a first side and an opposing second side, the firstside including a plurality of connection features arranged in an array,and a plurality of glenoid attachment members, each of the plurality ofglenoid attachment members having a locking mechanism; selecting one ofthe plurality of glenoid attachment members; and connecting the base tothe selected one of the plurality of glenoid attachment members byconnecting the locking mechanism of the selected one of the plurality ofglenoid attachment members to one of the plurality of connectionfeatures of the base.
 2. The method of claim 1, wherein the second sideof the base includes a locking feature, the method further comprising:using a plurality of offsets, each of the plurality of offsets having anarticulation side and an opposing coupling side, the opposing couplingside having a locking feature; selecting one of the plurality ofoffsets; and connecting the base locking feature to the opposingcoupling locking feature.
 3. The method of claim 1, wherein theselecting comprising selecting a plurality of glenoid attachment membersand connecting comprises connecting each of the plurality of glenoidattachment members to the base.
 4. The method of claim 1, wherein theplurality of connection recesses are generally spherical-shaped recessesand the locking member is a ball-shaped member and the connectingcomprises snapping the ball-shaped member into the generallyspherical-shaped recess.